I've read and studied poetry, much at the graduate level, for over 15 of my adult years and I've never heard of "plasticity poetry." Based on that--I read quite broadly--as well as the fact that even the site you cite offers no definition of it* confirms to me that no such thing exists.
* It has a link to a "definition of plasticity poetry," but it turns out to be a definition of "plasticity," which you could get from any dictionary. This is not helpful at all.
There are no "short plasticity poems" listed at their link, either. There is a long "plasticity poem" provided, but it turns out to be a Walt Whitman poem that simply uses the word "plasticity," which isn't helpful at all.
At most, the site you reference provides some poems that are either about plasticity or mention it. "Plasticity poetry" is not a genre.
Thank you. Your answer is persuasive. The reason that I thought it might be a genre is that was used in the last line of this sentence:
"You can discuss these types of poems".
But you're explanation resolve my suspect.